The present invention relates to a device, assembly and method for performing welding operations, wherein substances inconvenient to the welder are extracted.
Welding is generally the connecting of metals by means of heat and/or pressure, with or without the addition of similar material with the same melting range. In fusion welding the objects for welding are mutually connected by fusing of the material in the vicinity of the welding joint without pressure being exerted on the objects. The welding joint is filled with a metal which is supplied in wire or rod form. An important known fusion welding method is arc welding, wherein an electrical arc is used to fuse the edges of the welding joint and the supplied metal. In gas shielded arc welding, reactions of the melting bath with the outside air are prevented by enclosing the bath in a protective atmosphere.
The weld fume released during welding, consisting inter alia of gas supplied during the welding, by evaporation and condensation and by weld particles and welding gases and the like resulting from spatters, contains substances which can be irritating or even harmful to the health of the welder. Particularly in the case of frequent and prolonged welding, the quantity of harmful or irritating substance taken in by the welder is undesirably large.
Welding devices are known wherein just above the welding joint of the weldment for welding an extractor unit is placed which extracts the greater part of the weld fume. The drawbacks of such an extraction unit are that it is only effective when it is placed close to the welding device and that it is quite bulky. Certainly in the case of larger weldments, wherein a welding joint of great length must be made or welding must take place at large mutual distances, such an extractor unit is less effective. Such an extractor unit must moreover co-displace with the welding device via a mobile, rotatable, pivotable or slidable frame, which considerably reduces the mobility of the welder.
A weld fume dispelling device is also known which is arranged on the body of the welder and which blows away the weld fume directly in front of the face of the welder. The drawbacks of such weld fume dispelling devices are, among others, the limitation in the freedom of movement of the welder in that an apparatus is fixed to the body of the welder and the fact that, while the weld fume is dispelled, it nevertheless remains in the welding area in which the welder is carrying out his activities which, certainly in poorly ventilated welding areas, can result in too high weld fume concentrations.
Welding guns are also known wherein around a contact tube through which the welding wire required for the welding is supplied a gas feed is arranged for supplying shielding gases and wherein around the shielding gas feed an outlet is realized which attempts to discharge the substances inconvenient to the welder before they have reached the welder.
The drawback of such a welding gun is that the extraction force must be limited so as not to adversely affect the shielding gas, so that substances which are damaging to health or irritating are not sufficiently discharged and therefore reach the welder in large quantities.
The object of the invention is therefore to provide a device wherein the stated drawback is obviated. The present device provides for this purpose a device for performing welding operations, comprising:
a core member in which can be guided a welding wire connectable to a voltage source;
an extraction member arranged on the outside of the core member for extracting substances inconvenient to the welder;
a gas supply member arranged on the outside of the extraction member for supplying gas.
By so adapting the placing of the outlet, i.e. directly around the contact tube or core member, the protective gas arc on the one hand remains present round the welder, whereby oxidation and the like continues to be prevented, and on the other hand substances inconvenient to the welder are extracted in improved manner. The quantity of inconvenient substances actually reaching the welder will hereby be greatly reduced, which results in a greatly reduced effect on the health of the welder.
According to preferred embodiments of the invention the core member has a substantially elongate form, the extraction member is arranged substantially around the longitudinal side of the core member and the gas supply member is arranged substantially around the longitudinal side of the extraction member. This results in an elongate welding gun which is easily grasped and operated by a welder.
In a further embodiment the extraction member is a tube in which the outer casing is arranged substantially concentrically relative to the core member.
In a further embodiment of the invention the gas supply member is formed by at least one tube member arranged against the outer wall of the extraction member. This results in an easily and well manageable construction with which the objective of the invention can be achieved.
According to a further embodiment the gas supply member is formed by a tube arranged substantially concentrically relative to the core member and around the outer wall of the extraction member. By embodying the gas supply member and the extraction member as concentric tubes around the core member a simple construction is obtained with which the substances inconvenient to the welder are discharged in uniform manner, i.e. over the whole inner surface of the shielding welding arc. In a further embodiment of the invention the extraction member is formed by at least one extraction tube arranged against the outside of the core member and the gas supply member by a tube, the outer casing of which is arranged substantially concentrically relative to the core member.
The present invention also provides an assembly for welding a weldment which comprises the above described device, welding wire supply means for supplying welding wire, gas supply means for adding gas via the gas supply member, a voltage source for applying an electrical voltage between the welding wire and the weldment and pumping means for exhausting substances inconvenient to the welder via the extraction member.
The invention also provides a method for performing welding operations with the above described device or the above described assembly.